Norfolk Island Pine (Araucaria heterophylla), sometimes called living Christmas trees, are commonly grown as houseplants. They are fairly easy to care for, but once the leaves begin to yellow, the lower branches will eventually die and drop off. They will not turn back to green after they have reached this point. With proper care, you can avoid this condition and allow your plant to thrive indoors for many years.
Insufficient moisture in the air causes the needles of the Norfolk Pine to turn yellow and then brown before eventually falling off. Mist your pine with cool water daily to raise the humidity level. You can also run a humidifier near the plant to raise the humidity in the room. Norfolk Island Pines do well in 50-percent humidity. The plant should be watered frequently during the summer months to keep the soil slightly damp. Be careful to not over-water, as this may also cause the leaves to turn yellow. Do not let the soil get soggy. Water your plant weekly during the winter months, allowing the soil to dry completely between watering.
Norfolk Island Pine thrive in natural light. They prefer an eastern or western exposure with one to two hours of sunshine daily. Place your plant near a window for best results. They can also survive in household light if they receive at least 16 hours of light a day. Turn the plant frequently to keep it symmetrical.
Norfolk Island Pines grow best in a cool room with daytime temperatures between 60 and 72 degrees. Nighttime temperature should range between 50 and 65 degrees. Excessive heat could cause the leaves to yellow. Extreme changes in temperature could also harm your plant.
Norfolk Island Pines do not need to be transplanted very often. They typically take three to four years to outgrow their current pot. Only repot a Norfolk Island Pine if the roots begin to grow out of the bottom of the container. The leaves may turn yellow due to the shock of repotting. Always use a fast-draining, sterile commercial-grade soil and repot your plant in the spring. Norfolk Island Pines do not have a large, lateral root system and should be kept in a deep pot for support.